Malignant oral tumours in Sweden 1960–1989—An epidemiological study

Abstract Epidemiological data from the Swedish Cancer Registry of new cases of malignant oral tumours in Sweden 1960–1989 are presented, including the total number and the age-standardised incidence rate per 1 million population, by site and sex, (I (S) ). An analysis of the various histopathological types of malignant oral tumours in the different sublocations is also given. A comparison is made between the three 10-year periods 1960–1969, 1970–1979 and 1980–1989 regarding total number and I (S) . The total number of cases, 17 158, represented 1.8% of all newly diagnosed cancers in Sweden. The following relative frequencies were noted for the respective sites: intra-oral region 0.7%, lip 0.6% and pharynx 0.5%. The results indicated an increase in total number and a statistically significant increase of I (S) for malignant lip tumours in females over the whole period. A corresponding increase in total number during the periods 1960–1969 and 1980–1989 and a decrease in I (S) during the periods 1970–1979 and 1980–1989 in lip tumours for males was observed. For males there was an increase in total number and a statistically significant increase in I (S) for malignant tongue tumours, while the corresponding figures for females remained constant. For malignant floor of the mouth tumours there was an increase in total number and a statistically significant increase in I (S) for both men and women. In the intra-oral region, including the sublocations oral cavity-other sites, tongue and floor of the mouth, the male:female ratio was 1.8:1 and I (S) changed from 22.8 (1960–1969) to 29.6 (1980–1989). In the pharynx the male:female ratio was 2.4:1 with an I (S) of 29 and 12 cases for males and females, respectively. The most pronounced change in the male:female ratio was observed for the hypopharynx, where the ratio changed from 1.5:1 (1960–1969) to 4.9:1 (1980–1989). A marked increase in I (S) was found in the mesopharynx, from 3.7 to 7.8 when the periods 1960–1969 and 1980–1989 were compared. In the other sublocations of the pharynx, no corresponding statistically significant differences were found.